About
Most calculators do arithmetic you could do yourself. The formula is public, so the tool is a weekend's work for anyone — which is why every niche already has forty of them. This site is built the other way round.
What makes these different
The calculators here run on numbers we collect and refresh ourselves: figures that are scattered across public sources but that nobody has assembled, checked, or kept current. The arithmetic is the easy part and we give it away. The data is the work.
That has a consequence we think is worth stating out loud: these numbers go stale. A figure from six months ago is worse than today's, so every tool shows you the date its data was collected and where it came from. If that date is old, treat the answer as old.
How we handle being wrong
Every number we publish carries a confidence grade, and we track them the same way internally:
| Grade | Means |
|---|---|
| A★ | We measured it ourselves |
| A | A primary source — the vendor's own price list, the statute, the official filing |
| B | Two independent sources that agree |
| C | Directional only. A range, never a forecast. |
| ? | Genuinely unknown. We say so rather than estimating. |
When two sources disagree, we keep both and show the disagreement, because a conflict between two credible sources is more informative than whichever one we happened to read second. We do not quietly overwrite a number and hope nobody noticed.
How this is paid for
Advertising, and eventually sponsorship of the newsletter. That is the whole model. It means two things you are entitled to know: ads on this site are served by Google and are not endorsements, and no advertiser has ever seen a number before it was published, or changed one after.
Who makes it
Plain Reckoner is run by Plain Reckoner, one person, from Curitiba, Paraná, Brazil (residence). There is no team and no funding — which is the reason the work is narrow and the reason it can afford to be slow and correct rather than fast and approximate.
Corrections
If a number here is wrong, tell us and we will fix it and say what changed. Email [email protected]. A correction that changes a published figure gets noted on the tool itself, not buried.
Postal address: Curitiba, Paraná, Brazil · Privacy